Section 4 Dished ends subject to internal pressure

4.1.1 The thickness, t, of semi-ellipsoidal and hemispherical unstayed ends, and the knuckle section of torispherical ends, dished from plate, having pressure on the concave side and satisfying the conditions listed below, is to be determined by the following formula:

4.1.2 For semi-ellipsoidal ends:

the external height, H ≥ 0,18D_o

4.1.3 For torispherical ends:

the internal radius, R_i ≤ D_o

the internal knuckle radius, r_i ≥ 0,1D_o

the internal knuckle radius, r_i ≥ 3t

the external height, H ≥ 0,18D_o, and is determined as follows:

4.1.4 In addition to the formula in Pt 5, Ch 11, 4.1 Minimum thickness 4.1.1 the thickness, t, of a torispherical head, made from more than one plate, in the crown section, is to be not less than that determined by the following formula:

4.1.5 The thickness required by Pt 5, Ch 11, 4.1 Minimum thickness 4.1.1 for the knuckle section of a torispherical head is to extend past the common tangent point of the knuckle and crown radii into the crown section for a distance not less than , before reducing to the crown thickness permitted by Pt 5, Ch 11, 4.1 Minimum thickness 4.1.4

4.1.6 In all cases, H is to be measured from the commencement of curvature, shown in Figure 10.4.2 Typical dished ends.

4.1.7 The minimum thickness of the head, t, is in no case to be less than 3 + mm, where D_i is as defined in Pt 5, Ch 11, 1.2 Definition of symbols. The minimum thickness permitted for vessels manufactured in corrosion resistant steels will be the subject of special consideration.

4.1.8 For ends which are butt welded to the drum shell, see Pt 5, Ch 11, 1.9 Joint factors, the thickness of the edge of the flange for connection to the shell is to be not less than the thickness of an unpierced seamless or welded shell, whichever is applicable, of the same diameter and material and determined by Pt 5, Ch 11, 2.1 Minimum thickness.